Corolla Verso 2006 Semi Auto loss drive in gear 2

[Amitp]

Hello All,

I am new in this forum. I have Corolla Verso 2006 semi auto petrol 1.8 61K mileage. my car very occasionally loss drive in gear 2. I feel no movement even i put my foot down on gas while i am driving. i feel sound from the engine when apply more gas but no drive at all. so I need to shift it in "N" to and then back to "E" while the car is still moving. and the gear will start from 1 and then it's run well. I noticed that the problem happens mostly when i approached to roundabout with high speed so the gear will go down to 2 from 4 or 5 and when i continue to drive it doesn't change from gear 2 to 3. 

Yesterday I got transmission warning light but when turn the car off and on again it disappear and car runs fine. 

Now the issue is very difficult to explain to any local mechanic as this doesn't happened regularly.

Does anyone has got any idea of what needs to be done? does it sound the fault in the gearbox?